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Comparative uptake kinetics and transport of cadmium and phosphate in Phleum pratense‐Glomus deserticolum associations
Author(s) -
Arnold Paul T.,
Kapustka Lawrence A.
Publication year - 1993
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620120118
Subject(s) - phleum , phosphate , cadmium , glomus , divalent , kinetics , botany , biology , chemistry , biochemistry , spore , physics , organic chemistry , quantum mechanics
Mycorrhizal plants (timothy grass, Phleum pratense with Glomus deserticolum ) were compared to nonmycorrhizal timothy grass to determine the effect of the mycorrhizal condition on the uptake and transport of cadmium. Companion experiments were conducted to ascertain phosphate uptake kinetics of mycorrhizal and nonmycorrhizal plants. Divalent cation competition experiments also were employed in this study. Comparisons of the high‐affinity uptake mechanisms between mycorrhizal and nonmycorrhizal plants identified higher levels of phosphate uptake were due to an increase in the number of uptake sites rather than to differences in affinity. The respective values for K m for high‐affinity phosphate uptake were 2.5 ± 1.3 μM P (mycorrhizal) and 3.4 ± 1.3 μM P (non‐mycorrhizal), but these values were not statistically different at the α = 0.05 level. High‐affinity Cd 2+ uptake differed significantly between mycorrhizal (4.5 ± 2.8 μM) and nonmycorrhizal (2.8 ± 1.1 μM) plants. Presence of Ca 2+ at 1.0 mM concentration conferred considerable competitive protection in both the mycorrhizal and the nonmycorrhizal conditions. The effect of Ca 2+ was an approximate fourfold increase in the respective K m values.